The first of many patents for devices proposing to harness the power contained in ocean waves was issued in France in 1799. It was not until the 1970's that any considerable efforts were made to develop a viable and cost-effective technology. This was primarily driven by the increasing concern about the earth's finite fossil fuel resources and about environmental pollution resulting from combustion of such fuels.
There has been much interest in how to derive usable energy from solar, geothermal, wind and wave sources. The latter two offer the prospect of generating electricity and desalinating seawater by directly converting the kinetic energy of wind or waves to a useable form of power.
Ocean waves constitute an enormous reservoir of energy to be exploited. However, their random nature and the hostility of the marine environment have posed significant problems to the practical realization of a cost-effective wave energy conversion technology.
The greatest energy flux occurs in deep water waves that have been generated over uninterrupted fetches of the open ocean. However, the engineering challenges necessary to enable the equipment to survive in that environment have thus far proven to be insurmountable. Another reason is that deepwater structures must float and this reduces the conversion efficiency.
Although incident power reduces with decreasing depth, so do construction, installation and operating costs. It is for this reason that the practical limit appears to be about 20 meters of water depth. However, a viable design for a wave energy converter operating at this depth or any other depth has not yet been demonstrated as commercially viable.
U.S. Pat. Nos. 4,076,463 (Welczer), 4,754,157 (Windle) and 6,800,954 (Meano) describe various examples of wave energy devices providing a float for following the rise and fall of the waves which drives a pump to produce a usable flow of pressurized water. In each instance however, the floats are only able to capture the vertical movement of the water. Accordingly, a substantial portion of the wave energy in the form of surge forces in the direction of wave propagation is lost, resulting in poor operating efficiencies.
Some other prior art devices are known to provide a channel structure which is fixed in relation to the seabed to direct the wave energy towards a float member which similarly drives a pump. The float member in this instance is typically constrained by a pivot arm or a sliding rail structure. The cost of installation of such a configuration is typically prohibitive. Furthermore, the devices can be subject to considerable damage when left open to the elements due to the fixed nature of their installation.